| The noise of the automotive transmission gear whine is a regular problem in modern vehicle NVH region. Gear whine is medium to high frequency pure tonal noise. And although its Sound Pressure Level (SPL) is low, it is also easy to be feel subjectively by human ears, which makes it more difficult to control the gear whine. The NVH experimental approach is used to analyze the characteristics of gear whine in this research project, analyzing and researching the control methods of transmission gear whine from the views of gear design and manufacturing process.Firstly, this paper expounds the topic source, the research significance of controlling automotive transmission gear whine, the mechanism of whine production and control principles. Then the research progresses about controlling gear noise at home and abroad are introduced. The paper points out clearly the problems that need to be resolved, the main research contents and routs. The second chapter in this paper briefly introduces the following subjects:the definition of gear micro-geometry, the principle and structure of the gear micro-geometry measuring instrument-WENZEL, the noise and vibration measuring system-HEAD Acoustics and the subjective evaluation and objective measurement methods of gear whine noise. In addition, the fundamentals of acoustics and order tracking method in rotational machinery are also including, from which the order calculation methods of FWD and RWD transmissions are obtained.Some innovative experiments are carried out to research the characteristics of gear whine. Taking the C307、F5M42、452MT and JC520transmissions as the examples, the NVH experiments are carried and the results show that the SPL of the gear whine outside the vehicle increases linearly as rotational speed of input shaft rises, and vice versa. Based on the experiments results, harmonic distortion and gear vibration theories it can be concluded that only the fundamental order gear whine noise can be audible in compartment. The relationship between inner gear whine SPL and the whine frequency is analyzed on the basis of the absorption and transmission loss of sound on vehicle. The acceptable criterion of inner gear whine is obtained according to the acoustic masking effect and the critical band of human ear.The gear micro-geometries which influence on the gear whine noise are analyzed by the single factor analysis using RomaxDesigner software in the fourth chapter. The single factor analysis takes the5th gear pair on B299transmissions as an example. The analysis results are verified by the measurement in the gears manufacturing process. With the help of this method, the micro-geometries of5th gears on JC520TM24A transmissions are optimized, reducing the5th order gear whine noise in the compartment to13dB.It is the first time that the paper tests and analyzes the vehicle idle gear whine. According to the NVH measurement of C307idle status and its5th gear parameters, idle gear whine can occur when the5th gears have positive fTIF, bad gear lead and large deviation of different teeth on one gear. This paper does a quantitative research on the relationship between different gear manufacturing process and the gear whine noise control. With the final drive gear on452AMT transmissions for research object, the researchers manufactured the final drive gear with the shaving and grinding respectively. The normal distribution results of gear micro-geometry with the two different manufacturing indicate that the grinding process decreases the RMS deviation for1time, the uniformity is improved by the grinding and that the crossover on gear lead direction is eliminated. The gear whine SPL of final gear order in the compartment is reduced to3dB lower than that with shaving. However the SPL can be close to the level for lOdB reduction in some revolution regions. |
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